This invention relates to a structural unit having a net member of a three-dimensional structure incorporated therein, a sheet constructed of such a structural unit and a method for treating an end section of the net member.
A seat which is required to exhibit increased cushioning characteristics such as a seat for an automobile or the like is generally constructed in such a manner that a spring member such as a coiled spring, an S-shaped spring or the like is arranged on a seat frame, a pad member made of urethane resin or the like is arranged on the spring member and then a vinyl leather material, a fabric or the like overlies a front surface of the pad member. However, the seat thus constructed is increased in thickness and weight due to incorporation of the spring member therein. Also, the conventional seat is generally deteriorated in air permeability or ventilation unless any specific means such as formation of ventilation holes through the pad member is applied thereto. Such specific means for realizing ventilation in the seat causes an increase in manufacturing cost of the seat.
In order to solve the above-described problem, a seat was proposed which includes a net member of a truss structure (three-dimensional structure) constructed of a front mesh layer, a rear mesh layer and a plurality of piles arranged between the front mesh layer and the rear mesh layer to connect both mesh layers to each other therethrough. The truss structure permits the net member to be constructed into a resilient or elastic structure which is resistant to setting, so that the net member may exhibit characteristics of sufficiently dispersing and absorbing a pressure of the body. Thus, it exhibits significant cushioning characteristics while being formed into a reduced thickness. Also, it is constructed into a network structure, to thereby be provided therein with a number of voids, resulting in exhibiting good air permeability without providing any specific ventilation means therein.
Although the net member thus constructed into a three-dimensional structure exhibits such characteristics as described above, it not only has a number of the voids formed therein but is formed into a substantially increased thickness because of including the piles formed into a height in addition to the front mesh layer and rear mesh layer each formed into a thickness, so that it is substantially difficult to securely fix the net member to the frame. Conventionally, such fixing is generally carried out in such a manner as shown in FIG. 12. More specifically, an element 102 made of synthetic resin or iron is welded to an end section 101 of a net member 100 by vibration welding which is a kind of heat welding and then the net member 100 is fixed to a frame 104 by means of a screw 103 through the end section 101 having the resin or iron element 102 welded thereto.
However, such fixing is carried out in the form of a spot fastening; therefore, when load is applied to the net member 100 acting as a cushioning member for a seat due to sitting-down of a person on the net member or the like, the resin or iron element 102 fastened to the net member 100 through the screw 103 is exposed to stress at an increased magnitude. This possibly causes deformation of the resin or iron element 102 and/or damage to the net member 100. Thus, it should be avoided to apply load at a large magnitude to the net member 100. Also, such fixing or fastening by means of the screw 103 causes assembling of the seat to be troublesome, leading to an increase in manufacturing cost of the seat.
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a structural unit having a net member of a three-dimensional structure incorporated therein which is capable of preventing such application of local load or stress thereto as encountered in a net member using a fastening screw, to thereby enhance reliability of the net member.
It is another object of the present invention to provide a structural unit having a net member of a three-dimensional structure incorporated therein which is capable of facilitating assembling thereof and reducing a manufacturing cost thereof.
It is a further object of the present invention to provide a structural unit having a net member of a three-dimensional structure incorporated therein which is suitable for use for a seat for a vehicle or the like.
It is still another object of the present invention to provide a seat which is constructed of such a structural unit as described above.
It is yet another object of the present invention to provide a method for treating an end of a net member.
In accordance with one aspect of the present invention, a structural unit having a net member incorporated therein is provided. The structural unit includes a net member of a three-dimensional structure constituted by a front mesh layer, a rear mesh layer and a plurality of piles arranged between the front mesh layer and the rear mesh layer so as to connect the front mesh layer and rear mesh layer to each other therethrough. The net member is formed on a periphery thereof with an end section. The structural unit also includes an end holding member for supporting the end section of the net member therein. The end holding member includes a holding element formed therein with an insertion gap into which the end section of the net member is inserted. The end section of the net member is treated so that at least a part thereof has a net structure increased in density and rigidity as compared with a portion of the net member positioned inside the end section, resulting in being held in the end holding member due to insertion thereof into the insertion gap of the end holding member.
Also, in accordance with this aspect of the present invention, a structural unit having a net member incorporated therein is provided. The structural unit includes a net member of a three-dimensional structure constituted by a front mesh layer, a rear mesh layer and a plurality of piles arranged between the front mesh layer and the rear mesh layer so as to connect the front mesh layer and rear mesh layer to each other therethrough. The net member is formed on a periphery thereof with an end section. The structural unit also includes an end holding member for supporting the end section of the net member therein. The end holding member includes a holding element formed therein with an insertion gap into which the end section of the net member is inserted. The end section of the net member is fixedly mounted on at least a part thereof with a synthetic resin element by heat welding, so that the part of the end section on which the synthetic resin element is mounted is inserted into the insertion gap of the end holding member, resulting in the end section being held in the end holding member.
Further, in accordance with this aspect of the present invention, a structural unit having a net member incorporated therein is provided. The structural unit includes a net member of a three-dimensional structure constituted by a front mesh layer, a rear mesh layer and a plurality of piles arranged between the front mesh layer and the rear mesh layer so as to connect the front mesh layer and rear mesh layer to each other therethrough. The net member is formed on a periphery thereof with an end section. The structural unit also includes an end holding member for supporting the end section of the net member therein. The end holding member includes a holding element formed therein with an insertion gap into which the end section of the net member is inserted. The end section of the net member is treated so that a part thereof has a net structure increased in density and rigidity as compared with a portion of the net member positioned inside the end section and the end section is fixedly mounted on another part thereof with a synthetic resin element by heat welding, so that the parts of the end section may be held in the end holding member due to insertion thereof into the insertion gap of the end holding member.
In a preferred embodiment of the present invention, the insertion gap of the end holding member has an insertion port arranged in a posture which permits the end section of the net member to be inserted into the insertion gap therethrough while keeping the end section inwardly folded when the net member is arranged in contact with an outer surface of the net member.
In a preferred embodiment of the present invention, wherein the end section treated so that the net structure is increased in density and rigidity is formed on at least one surface thereof with a projection. The holding element is provided thereon with a pawl in a manner to project into the insertion gap of the end holding member. The end section is inserted into the insertion gap so that the projection is positioned deeply beyond the pawl in the insertion gap, resulting in being held in the insertion gap.
In a preferred embodiment of the present invention, the part of the end section treated so that the net structure is increased in density and rigidity is held in the end holding member positioned on a side on which stress occurring is reduced and the part of the end section mounted thereon with the synthetic resin element is held in the end holding member positioned on a side on which stress occurring is increased.
In a preferred embodiment of the present invention, the end section is treated so as to be reduced in thickness by heat welding, so that the net structure is increased in density and rigidity.
In a preferred embodiment of the present invention, the end section is subject to the heat welding after it is previously knitted so as to increase density of the net structure.
In a preferred embodiment of the present invention, the heat welding is carried out by vibration welding.
In accordance with another aspect of the present invention, a seat is provided. The seat is constituted by the structural unit constructed as described above.
In a preferred embodiment of the seat of the present invention, the end section treated so as to increase density and rigidity of the net structure is held in the end holding member connected to a frame forwardly arranged and the end section on which the synthetic resin element is mounted is held in the end holding member connected to a frame rearwardly arranged.
In a preferred embodiment of the seat of the present invention, the end section held in the end holding member connected to a frame laterally arranged is treated so that a net structure thereof is increased in density and rigidity, and is held in the end holding member after it is provided with the projection.
In accordance with a further aspect of the present invention, a method for treating an end section of a net member is provided. The method includes the step of reducing a thickness of an end section formed on a periphery of a net member of a three-dimensional structure by heat welding so as to hold the end section in an end holding member, resulting in a net structure of the end section being increased in density and rigidity as compared with a portion of the net member positioned inside the end section, wherein the net member is constituted by a front mesh layer, a rear mesh layer and a plurality of piles arranged between the front mesh layer and the rear mesh layer so as to connect the front mesh layer and rear mesh layer to each other therethrough.
In a preferred embodiment of the method of the present invention, the end section is subject to the heat welding after it is previously knitted so as to increase density of the net structure.
In a preferred embodiment of the method of the present invention, the end section is formed thereon with a projection in a manner to project in a thickness direction thereof during heat welding of the end section.
In a preferred embodiment of the method of the present invention, the heat welding is carried out by vibration welding.